Loss of power line triggers blackouts in Calif

August 26, 2005

By Nigel Hunt

LOS ANGELES (Reuters) – Blackouts were ordered in southern
California on Thursday afternoon following the loss of a major
transmission line with about 500,000 homes impacted for almost
an hour before service was restored.

The California Independent System Operator ordered southern
California utilities to immediately shed 900 megawatts of load
around 4 p.m. Pacific time (2300 GMT) following an outage on
the DC Pacific Intertie, which carries vital imports of
electricity from the Pacific Northwest.

Rosemead, Calif.-based utility Southern California Edison
took the bulk of the load reduction, about 800 MW, resulting in
between 400,000 and 500,000 customers losing service, a
spokesman for the utility said.

SCE is a unit of Edison International.

The Los Angeles Department of Water and Power, the nation’s
largest municipal utility, is not under the control of the
California ISO and did not order blackouts.

San Diego Gas and Electric, a unit of Sempra Energy cut off
service to about 50,000 customers.

The California ISO, which operates most of the state’s
power grid, said load also was reduced by about 800 MW through
service curtailments to certain business customers who receive
power at a discount in return for agreeing to reduce usage due
supply shortages.

The DC line, which brings imports of electricity from
Oregon into California, was taken off line following a problem
with a converter at its southern terminal near Los Angeles, a
spokeswoman for the LADWP said.

The LADWP operates the southern section of the line while
its northern terminal is operated by a federal agency,
Bonneville Power Administration.

The line was carrying about 2,250 MW when it went down, she
added, noting that within 20 minutes the utility had managed to
bring the line back up with a reduced limit of about 1,000 MW.

The California ISO said it ordered an end to the blackouts
at around 4.35 p.m. and SCE had fully restored service to its
customers by 4.55 p.m.

The grid operator, said loads in southern California were
running about 2,000 MW above forecast due to temperatures which
were up to 14 degrees Fahrenheit higher than anticipated.

Demand climbed to 44,650 MW on Thursday, just shy of the
all-time record of 45,754 MW which was set on September 8,
2004. Earlier projections had put demand for electricity on
Thursday at only around 41,000 MW.